Transitions not working correctly on Svelte next

[superboss224]

Describe the bug

There is a bug present in the latest next version, ^5.0.0-next.25

Here, on Svelte 4, the transition works correctly :
https://tabby-4.vercel.app/

But with Svelte 5.0.0-next.25, it doesn't work anymore :
https://tabby-5.vercel.app/

I took this example from here :
https://svelte.dev/repl/51f426b2a9404527aaad8093a62d3993?version=3.34.0

And here is the github repo of https://tabby-5.vercel.app/, where the bug is present:
https://github.com/superboss224/tabby-5-bug

I believe it comes from the transition's parameters not being reactive when those parameters are updated

Reproduction

https://github.com/superboss224/tabby-5-bug

Logs

No response

System Info

npmPackages:
  svelte: ^5.0.0-next.25 => 5.0.0-next.25

Severity

blocking an upgrade

[trueadm]

Thanks, I'll take a look when I'm back after the holidays :)

[adiguba]

I also encountered a problem mixing transitions and animations.

This work in Svelte 4 : REPL

But it don't work in Svelte 5 : REPL

• animate:flip is not executed, causing a visual bug.
• I got an error when I select a date after the current selected date.

Stacktrace :

Uncaught TypeError: block is undefined
    update_each_item_block playground:output:3214
    reconcile_tracked_array playground:output:3019
    clear_each playground:output:2740
    execute_signal_fn playground:output:291
    execute_effect playground:output:436
    each playground:output:2779
    execute_signal_fn playground:output:291
    execute_effect playground:output:436
    flush_queued_effects playground:output:487
    flush_local_render_effects playground:output:570
    pre_effect playground:output:962
    execute_signal_fn playground:output:295
    execute_effect playground:output:436
    flush_queued_effects playground:output:487
    process_microtask playground:output:506
    schedule_effect playground:output:527
    mark_signal_consumers playground:output:736
    set_signal_value playground:output:798
    set playground:output:679
    on_click playground:output:3433
    handle_event_propagation playground:output:2483
    event_handle playground:output:2614
    mount playground:output:2626
    <anonymous> playground:output:3547
    handle_message about:srcdoc:88
    EventListener.handleEvent* about:srcdoc:134
    <anonymous> about:srcdoc:143

[adiguba]

Another example I found using multiple if/else : REPL

Click on buttons A/B/C to change state.

• Transitions from A to C or C to A are OK.
• Transition from A to B are incorrect (slide on B is not executed).
• Transition from B to A are correct, but the C block is visible during the transition (should not be here).

[trueadm]

@adiguba I've landed some changes that should fix/improve the issues you were seeing. Let me know please if there's anything I missed.

[brunnerh]

The if/else example mentioned still has serious issues.
Transitions can be skipped or worse, not happen at all, with the UI showing the wrong element.

[trueadm]

@brunnerh Looks to work the same as Svelte 4 for me?

[adiguba]

The if/else REPL is also buggy for me

The first change from C to B is correct, but other change between B and C are not rendered.

Also the example mixing transitions and animations are different from Svelte 4.
It seem that the "out" transition is not rendered correctly.

[trueadm]

Ah I found an edge case I missed. This stuff is complex to get right fully!